This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Objective: To target the Wisconsin National Primate Research Center's mission to develop treatments for human disease, generate knowledge of primate biology, and to facilitate the progress of research by providing expertise and resources to external scientists, we are developing a methodology that we will use to determine the abundance and in situ localization of CD4 T cells specific to simian immunodeficiency virus (SIV) in tissues during SIV infection. Results: Although we have not yet received the pilot grant money from the WNPRC for the project, we have nonetheless started to make some progress. In collaboration with Marc Jenkins at the University of Minnesota we are developing methods to stain antigen specific CD4 T cells in spleen tissues from T cell receptor transgenic mice and Nancy Wilson at the WNPRC is making progress developing class II reagents for use in SIV-infected macaques.